Expedited is just a word. It is not a technical term. If you want to make it a technical term then you have to define it precisely as to context and scope.

Emergency is just a word and so is urgent. They are used in ITIL literature with more specific meaning but still not in a way that can be a technical term.

As far as I can see you could use any one of these to label a process through which a change can be applied in a shorter time than can be achieved by your "normal" Change Management process.

Equally you could have a section in your "normal" change management process which starts something like this:

"In circumstances where the there will be considerable cost (or loss of benefit) due to the time required to follow this procedure, the steps may be accelerated, subject to authority for the additional risks involved in such action..."

and then detail what kind of shortcuts are permissible under what authority.

And set up a strong review mechanism for such events to ensure it is not abused._________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718

If you are talking about a classification used by one of the Service Management tool providers, you would be talking about changes where lead times haven't been met. You need to remember, and remind people that changes which are poorly planned have a significantly higher fail rate, and if you are measuring change success, this matters a lot.
Hope this helps_________________DYbeach
ITIL V3 Release, Control & Validation,
ITIL V3 Operation SUpport & Analysis
PMI CAPM (R)

"In times of universal deceit, telling the truth will be a revolutionary act." George Orwell

I believe that my original response covers this question._________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718

I use the concept of a fast track release - business not service critical changes, by having a separate category it makes them easier to identify and measure which is useful for managing risk and recording as part of a KPI.

In my organization I was asked to own global change management where we had 4 different practices for "normal" vs "emergency" requests. In one of the practices, the "Emergency" workflow was very much abused to the point that hundreds of requests were circumventing the standard process. In order to get a better handle, a consolidation effort was required in order to streamline the process. We now have ONE established process/policy that includes a very stringent and executive sponsored emergency change process and since inception we have seen a 75% reduction in "emergency" requests. Ultimately the bottom line is that you will need to define the process that best works for your organization